What they both saw was this. A band of some twenty men, members of Morgan's corps, stood in groups on the extreme edge of the plain. At a given signal a horseman issued in a canter from their midst. The animal was almost pure white, with small, well-proportioned head, small clean hoofs, long haunches, abundant mane and sweeping tail. Every limb was instinct with speed, while the pricked ear, rolling eye and thin pink nostril denoted intelligence and fire. The rider was arrayed in the full uniform of a rifleman--grass-green coat and trousers, trimmed with black fur, through which ran a golden tape; crimson sash with white powder horn attached; a black turban-shaped hat of medium height, flanked over the left temple with a black aigrette of short dark feathers, which was held by a circular clasp of bright yellow metal. The rider trotted around leisurely in a long eclipse until the snow was sufficiently beaten for his purpose. He then indulged in a variety of extraordinary feats, each of which seemed to be demanded of him by one or the other of his companions. Among these the following may be worth enumerating. He launched his horse at full speed, when suddenly loosening his feet from the stirrups and his hand from the bridle, he sprang upwards and threw himself with both legs now on the left, then on the right of the saddle. He leaned far forward on the horse's neck so that the two heads were exactly parallel, and next fell back into the saddle facing the crupper and holding on to nothing. He stopped his horse suddenly and made him stand almost perpendicular on his hind legs. Then, without the assistance of bridle, stirrup, or pommel, he secured his position and made the animal plunge wildly forward as if he were clearing a high hurdle, while he no more swerved from his seat than if he had been pinioned to it. Setting his horse again at his topmost bent, he took his pistol, threw it into the air, caught it on the fly, and finally hurled it with all his might in front of him. Then slipping one foot from the stirrup, he bent his body over to the ground, seized the weapon as he passed, recovered his position and replaced the pistol in its place, before reaching the end of his round. The friends of the rider were not more intent in their observation than were the two spectators on the slope of the Citadel. "Marvellous horsemanship," exclaimed Hardinge with enthusiasm. "The animal must be an Arabian or some other thoroughbred. Whose can he be? There is no such horse in these parts or I should have known it. And yet it is hardly possible that he should have come along with Arnold's expedition." "And the rider?" murmured Pauline, advancing several steps in the earnestness of her gaze. "Yes, the rider," continued Roderick. "See he lives in the horse and the horse in him. They seem to form part and parcel of one another. A magnificent fellow." "Impossible," said Pauline, shading her eyes with her hand to sharpen her vision. "It cannot be."